The top U.N. humanitarian official says the relief effort in Sudan's Darfur region is on the verge of collapse because of a lack of funds and government restrictions on aid workers.

In a dire message to the U.N. Security Council Thursday, Jan Egeland, the United Nations Undersecretary for Humanitarian Affairs, said more than 200,000 people who need food to survive are not getting it, and some 650,000 people are beyond the reach of aid workers.

Egeland said relief efforts in many areas of Sudan will collapse within a matter of weeks because of violence, intimidation and a lack of money.

"The way it is now it can not continue," he said. "We need security, which we do not have. We need a government that enables us to work and does not create obstacles to our work. We need a guerrilla (force) that does not specialize in hijacking relief trucks and fighting each other and displacing new people, which has happened in the past few weeks. And we need funding."

Egeland said that just 20 percent of relief work in Darfur has been funded this year. He said Britain is the only nation that has increased its share of funding over last year. When asked why international support had fallen, the U.N. humanitarian chief said some donors may lack the willingness to sustain long-term commitment to such efforts.

"Maybe this world in 2006 is only able to run sprints and no marathon. Because this is a marathon," he stressed. " In 2005 we had more diplomatic support than we've had so far in 2006, and more funding. We've had more pressure on the parties than we've had this year."

Earlier this month, Sudan's government refused to let Egeland visit Darfur. Egeland said at the time he suspected the government did not want him to see what was happening there.

Three years of fighting in Darfur between rebels, government forces and Khartoum-backed Janjaweed militias has claimed an estimated 180,000 lives and left another two million homeless.